The present invention relates to linear displacement sensors and in particular to Hall effect linear displacement sensor utilizing DC input power and providing DC output. The sensor translates a variable linear core displacement to one or more DC outputs. Multiple output sensors find use as primary control elements in aircraft and other applications requiring one or more output signals. Heretofore the prevalent sensor for such applications consists of several linear variable differential transformers (LVDTs) assembled in parallel configuration.
Such a system is shown in U.S. Pat. No. 4,807,516 to Imre Takats. This patent discloses an aircraft flight control system employing three controllers operating as dual actuators. FIG. 1 of Takats depicts two dual LVDT assemblies which are AC devices requiring an AC power source for input power excitation and requiring a demodulator for output voltage measurement. Each of the LVDTs requires a separate core-rod assembly and parallel core-rod assemblies are attached to a yoke containing a ball bearing assembly for attachment to a single rod. Many aircraft control system include dual, triple or quadruple LVDT systems.
The prior art also includes a lateral displacement of a permanent magnet inducing a flux flow through a Hall effect device which in turn generates an output voltage indicative of the position of the permanent magnet with respect to the Hall effect device. Such arrangements are generally taught in U.S. Pat. Nos. 4,319,236 ; 4,107,604 and 4,322,709. The later reference relies on a magnetic circuit having a variable air gap with an increasing magnetic flux density used to activate a switch.